The current economic pressure on agriculture to produce foods cheaper, results in labor saving animal husbandry techniques which leave large populations of poultry at risk of contracting communicable diseases, often more than one disease at a time. When this does occur, and a farm flock is infected with concurrent infections, the results are usually devastating in regard to lost animals and lost production performance. Currently utilized vaccine technology has not resulted in an effective means to control this risk of concurrent infections.
Modified live vaccines have the advantage of being able to be applied or administered in the drinking water. However, certain drawbacks do exist. First, live vaccines can cause clinical disease particularly when they are delivered to birds that are stressed from either environmental problems or concurrent infections. Second, the administration of live vaccines in drinking water requires that the birds be vaccinated in a relatively short period of time, usually 2 to 4 hours, because live vaccines can die in the drinking water system used to water the birds. Thus, this often results in a situation where all the birds in the barn are not receiving an immunizing dose of the vaccine because they may not be drinking enough water during the period of time that the vaccine is being delivered. Third, since certain live vaccines (e.g., bacterial antigens) are susceptible to antibiotics, the birds typically cannot have received any antibiotic for 3 to 5 days prior to, or after, vaccination. The problem this creates is exemplified by a producer who has just spent money to vaccinate a flock against a disease using a live vaccine, and the next day the birds are showing signs of a digestive infection which could be easily treated with antibiotics. Unfortunately, if the producer treats the birds with antibiotics, the immunizing effect of the vaccine is lost. In addition, most live vaccines must be refrigerated during storage and shipping.
Inactivated vaccines that are administered parentally have the advantage that they can be delivered while the birds are being treated with antibiotics. However, this approach also has significant drawbacks associated with it. First, the obvious expense that is associated with handling individual birds in the vaccination process results in multiplying the cost 2 to 3 times over a mass vaccination approach such as used in modified live vaccines. Second, when the birds are going through a stress period, either environmental in nature or due to a concurrent infectious disease, the handling required for injecting individual birds can result in significant exacerbation of the clinical problem. Third, the risks associated with accidental injection of the vaccines to the people administering them has long been known, with some people losing fingers from severe inflammatory responses. Generally, inactivated vaccines also require refrigeration to prevent the adjuvant system from going rancid or breaking down in some other fashion.
Therefore, there is a need for an effective poultry vaccine that can be safely administered to a population of birds without exacerbating a stressful situation into a clinical problem. There is also a need for a vaccine that can be administered with antibiotics without detrimental effect to the immune response to the vaccine antigen. There is a further need for clinically useful vaccines which do not require refrigeration during storage or transportation. These and other needs are addressed by the present invention.
The present invention is directed to vaccine compositions and methods for safe and effective immunization of large populations of animals, particularly birds, through their drinking water.
It will be noted that at several places throughout the present specification, guidance is provided through lists of examples. In each instance, the recited lists serve only as a representative group. It is not meant, however, that the lists are exclusive.
A vaccine composition according to the invention includes an inactivated bacterin and a preservative. In one embodiment, the bacterin is present in one gallon of the vaccine composition at a concentration permitting a spectrophotometric transmission reading of up 12% at 540 nanometer per 10,000 doses of the vaccine. The inactivated bacterin can be derived from Escherichia Coli, Bordetella avium, a combination of Bordetella avium and Ornithobacterium rhinotrachaeale, Riemerella anatipestifer and Pasteurella multocida. Other bacterins suitable for the invention will become apparent to one of skill in the art after reading the present patent disclosure.
The vaccine composition preferably also includes a preservative. In one embodiment, the preservative is methyl/propyl paraben. In addition, a vaccine composition of the invention can also include an antibiotic.
The invention also provides a method for immunizing poultry with a vaccine composition of the invention in the drinking water of poultry. The vaccine composition can be administered to provide a priming immunization or booster immunization to the birds.
To be clinically useful, an immunization system should preferably be safe, simple to perform, cost effective and clinically effective in preventing the targeted disease. The present invention provides such an immunization system.
Oral tolerance is a theory which explains why animals do not usually develop immune responses to the food they eat. This theory fosters the notion that orally dosed antigens do not result in meaningful immune protection against an inactivated antigen that is orally administered. However, in contrast to the traditionally held notions regarding orally administered antigens, the present invention provides compositions and methods for the safe and effective administration of an inactivated vaccine through an oral administration route.
In general, the compositions of the invention can be administered to mass populations of animals through their drinking water, over a 12-24 hour period, with confidence that all animals are receiving an effective immunizing dose of the vaccine. The vaccines can be administered to young animals or adults as a primary immunizing agent, or as a booster immunizing agent as needed. Advantageously, the vaccine compositions of the invention do not require refrigeration and thus can be cost effectively stored with little concern regarding efficacy if not administered immediately upon opening.
In a preferred embodiment the methods of the invention are particularly advantageous for administration to poultry. As used herein, the term xe2x80x9cpoultryxe2x80x9d includes chickens, turkeys, pheasant, geese, duck, etc. The methods are particularly advantageous for use with intensive management operations of mass populations of birds.
As used herein, the term xe2x80x9cbacterinxe2x80x9d refers to a suspension of killed or attenuated bacteria. A bacterin according to the invention can also include a component of the bacteria, for example, fragments or components isolated from the whole organism, specific antigens genetically engineered, etc. In most preferred embodiments, the bacterin is an inactivated whole organism. In addition, the term xe2x80x9ctoxoidxe2x80x9d refers to a toxin produced by an organism. Typically, a bacterin of the invention will also contain the toxins produced by the organism. In fact, as described below, the invention provides methods for increasing the level of toxins in the bacterin for enhanced immunogenicity.
Examples of disease conditions which can effectively be controlled by the compositions and methods of the invention include respiratory diseases, gastrointestinal diseases, central nervous system disease, etc. Respiratory disease problems which can typically arise in confinement housing operations include mortality, morbidity, loss of performance (i.e., decreased rate of gain or feed conversion), and loss of wholesomeness due to chronic airsaculitis.
Typically, the infectious components of respiratory disease of turkeys include Bordetella avium (BART), primary or virulent serotypes of Escherichia coli (serotypes 01, 02, and 078), Ornithobacterium rhinotracheale (ORT), Newcastle Disease Virus, Avian Pneumo virus, and perhaps other not yet identified agents.
BART is a disease which has its most significant clinical affects if the birds are initially infected in the first few weeks of life. Early infection can result in denudation of the tracheal cilia which can exacerbate the pathogenicity of respiratory organisms because of the birds"" inability to clear the infection from the respiratory tract. Primary E. coli can result in severe clinical disease by itself, but is much more severe when the birds are infected with BART. It has been hypothesized that a severe infection with toxigenic E. coli can result in direct damage to the heart muscles and develop a condition known as xe2x80x9cflabby heartxe2x80x9d or cardiac dilatation.
ORT causes the most severe clinical disease when the birds are first infected as young adults, seventeen to eighteen weeks of age. This disease can result in severe pulmonary inflammation which can interact with the primary E. coli and put more pressure on the heart muscles resulting in more severe cardiac dilatation.
Newcastle disease virus is not seen as a significant disease unless it is acting in concert or at the same time as another respiratory disease.
Pneumo virus is also viewed as not significantly pathogenic unless it interacts in birds with one or more of the other respiratory pathogens listed above.
Prior vaccine technology has not resulted in effective means of dealing with all these potential interactive respiratory diseases of confinement animals. The present invention is directed to addressing the problems with prior immunization systems through oral administration of an inactivated antigen. In addition, to being contrary to traditional oral tolerance theories, a significant hurdle in attempting to develop the present vaccine systems was the difficulty in measuring mucosal immune responses. That is, it was extremely difficult to evaluate specific oral antigen concentrations required to produce optimum mucosal immune response. The inventor has overcome this hurdle by using the lack of systemic immune response to evaluate the efficacy of the inactivated orally dosed bacterins disclosed herein. As described in the Examples, farms having a history of severe infectious disease problems and subsequent disease problems were studied to confirm the efficacy of the composition and methods of the invention.
In the case of BART, when orally dosing the presently disclosed inactivated BART bacterin, the flocks on the immunized farms were negative for BART using ELISA tests which measured circulating or systemic antibodies. Based on this information, turkeys vaccinated with the inactivated BART bacterin did not result in circulating or systemic antibodies. Thus, the BART bacterin was successful in preventing BART from becoming a systemic infection by blocking the disease at the surface or at the mucosal level. Because there is no convenient ELISA test for E. coli, the same antigenic concentration used for the BART bacterin was also used to develop an E. coli bacterin with similar clinical success.
Additional vaccine compositions of the invention include inactivated bacterins comprising Reimerella anatipestifer; a combination of Bordetella avium and Ornithobacterium rhinotracheale; and Pasteurella multocida. In view of the present disclosure, other vaccines within the scope and spirit of the invention will apparent to one skilled in the art.
The bacterins of the invention are prepared from bacterial cultures grown on a suitable culture media. Most media suitable for propagation of a particular organism are suitable for the invention. The bacterial cultures are screened to establish the purity of a particular organism and the organisms are inactivated. Methods of inactivation useful according to the invention, include, for example, formalin treatment, heat treatment, hypochlorite treatment, irradiation, and other methods known in the art. In a preferred embodiment, the organisms are inactivated with 0.3%-0.4% v/v formalin.
The antigenic content of a composition of the invention can be determined using most known methods for ensuring a particular antigenic concentration. In a preferred method, the antigenic content is measured using a spectrophotometer reading at a wavelength of 540 nanometer. In general, a suitable concentration of the antigen is about 1%-15%, preferably about 2%-10% transmission at 540 nanometer.
Preservatives may also be added to a vaccine composition. Most known preservatives are suitable. However, in a preferred embodiment, methyl/propyl paraben is used. The preservative can also include red food-grade dye. In one particularly preferred embodiment, the preservative comprises methyl/propyl paraben containing 1-2% red food dye. The preservative combination is preferably present in the vaccine composition at a concentration of about 1%-2% v/v.
Antibiotics can also be added to the vaccine composition. Suitable antibiotics include penicillins (e.g., penicillin, ampicillin, amoxicillin, etc.), cephalosporins, aminoglycosides (e.g., gentamycin, streptomycin, amakacin, etc.), sulfas, tetracyclines, etc. In some preferred embodiments a suitable, cost effective antibiotic system is penicillin and streptomycin.
The vaccine compositions are preferably bottled in an easy to use container having a sufficient number of dosages for the particular application. Generally screw top one gallon plastic bottles can be used. The compositions can be formulated to contain 5,000-30,000, typically about 10,000 to 20,000 doses per gallon. To provide an adequate dosage to a flock of about 20,000 birds, 1 gallon of a 20,000 dose container is mixed with the amount of water the birds would consume in 24 hours. Thus, the concentration of the vaccine composition in the water supply for younger birds (lower body weight) will be greater than that for birds of a higher body weight due to lower overall water consumption in younger birds.
In one embodiment, one gallon of a vaccine composition containing sufficient antigen at 9% transmission at 540 nm is administered to 10,000 birds over a 24 hour period every 3 to 7 days for the life of the bird. In another embodiment, a one gallon composition containing sufficient antigen at 3.5% transmission at 540 nm is administered to 20,000 birds over a 24 hour period every 3 to 7 days for the life of the bird.
According to the invention, the frequency that the birds are immunized with a vaccine composition of the invention can vary with the perceived challenge of a pathogenic organism. Thus, if the perceived level of challenge is high, the frequency of reimmunization is preferably increased.